After Internet Information Services (IIS) is restarted, the Cisco CallManager user login authentication fails. The Cisco CallManager user cannot log in from the CallManager user logon page with correct user ID and password after some idle period time. No users can log in thereafter. The problem is observed in Cisco CallManager 3.3(2) and 3.3(2).
These symptoms are addressed in Cisco bug ID CSCdz56517: CCMUser logon authentication failure in case of Active Directory (AD).
It occurs when the connection to the Lightweight Directory Access Protocol (LDAP) server fails. This issue has been corrected in Cisco CallManager 3.3(3). The workaround is to restart IIS on Cisco CallManager.
Alternatively, upgrading the Cisco CallManager to version 3.3(3) helps resolve the issue.